The present invention relates generally to the field of water supply systems. In particular, the invention relates to the control of temperature of a hot-water supply system.
In water supply systems installed in many homes, water is made available at one or more outlets, such as sinks, tubs, showers or appliances, through a cold water line and a hot water line. Typically, water enters the supply system from a source, such as a well or a water main, and is directed, on the one side, to a cold water line and, on the other side, to a water heater. Hot water from the water heater is then directed to a hot water line. The hot and cold water lines are then mixed at the outlet to provide water at a desired temperature.
In many systems, particularly those in large homes, hot water may not be immediately available at all outlets at all times. For example, water in the line between the water heater and an outlet may cool to room temperature overnight. Hot water does not become available at an outlet until the cooled water in the line is first drawn and wasted. This problem may be particularly apparent at an outlet that is furthest from the water heater. At such an outlet, the amount of cooled water that must be drawn before hot water becomes available may be quite large.
Systems to prevent such waste have been proposed. For example, U.S. Pat. No. 6,536,464, which is hereby incorporated by reference, proposes a thermostatically controlled bypass valve positioned within a tubular body between the hot water side and the cold water side. The valve opens a passage between the hot water side and the cold water side when the hot water is too cool. However, the bypass valve is positioned well within the tubular body and cannot be accessed for adjustment of the temperature at which the valve should close.
It is desirable to provide a means for controlling the temperature at which hot water is allowed to flow through an outlet.